Why is washing soda used to soften hard water?
Answer and explanation
Correct answer: It helps remove calcium and magnesium ions
The governing concept is removal of hardness-producing ions by precipitation. Hard water contains dissolved calcium and magnesium ions, which react with soap to form scum and prevent lather. Washing soda, sodium carbonate, supplies carbonate ions that can form sparingly soluble calcium carbonate and magnesium carbonate, removing these ions from the water. Therefore option A is correct. It does not convert water into gas, generate oxygen, or soften water by making it acidic.
Frequently asked questions
What is the correct answer to this question?
It helps remove calcium and magnesium ions
Why is this the correct answer?
The governing concept is removal of hardness-producing ions by precipitation. Hard water contains dissolved calcium and magnesium ions, which react with soap to form scum and prevent lather. Washing soda, sodium carbonate, supplies carbonate ions that can form sparingly soluble calcium carbonate and magnesium carbonate, removing these ions from the water. Therefore option A is correct. It does not convert water into gas, generate oxygen, or soften water by making it acidic.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Acids, Bases, and Salts.
